Poly(vinyludene fluoride-co-hexafluoropropylene) (PVdF-HFP) Porous polymer electrolyte membranes were prepared by the solvent-nonsolvent evaporation technique. The particle size and molecular weight of the polymer were greatly varied with the ball-milling technique, and the electrochemical properties of the polymer electrolyte membranes were examined as functions of these variations. The high hydrophobic nature of the host polymer is responsible for the high-temperature application and low methanol permeation. A hydrophilic nature was imparted to the fabricated porous membranes through activation with silica sulfuric acid liquid electrolyte. A decrease in the molecular weight effectively reduces the viscosity and is responsible for high ion migration. In addition, a decrease in the particle size lead to an effective acidification, so that the acidified polymer could effectively promote the ionic conductivity further. A much lower fuel permeation associated with the high ionic conductivity of the ball-milled membranes facilitates the performance of direct methanol fuel cells and Supports their potential application therein.